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Better bubble business: CO2 capture turned a waste stream into an income stream at Denver Beer.

If you tour a craft beer brewery, you’ll often see a long hose leading from the top of a fermentation tank down into a bucket of frothy, bubbling water. The water prevents air from flowing back into the tank, which could spoil the batch. The bubbles are carbon dioxide, a by-product of the yeast’s alcohol-making activity. Most small breweries release the CO2 into the air as waste.

That waste bothered Charlie Berger, cofounder of Denver Beer. He didn’t like adding that carbon to the atmosphere or that he had to then turn around and buy compressed CO2 to carbonate the beer as it went into bottles and kegs.

Larger operations capture and reuse the CO2 from fermentation to carbonate their beverages, but the systems they use are expensive. Below an annual volume of around 100,000 barrels of beer per year, that equipment doesn’t make financial sense, says Diana Alexandrov of beverage engineering firm ICC Group. Around 98% of breweries are at or below that scale, according to 2016 data from the US Alcohol and Tobacco Tax and Trade Bureau.

Robert Zubrin of Pioneer Energy saw an opportunity in the gassy conundrum. He had worked with NASA on ways to collect, purify, and liquefy CO2 on Mars. He and his team adapted that technology into a system that could recover 4.5 metric tons of brewery CO2 per month. Pioneer licensed that technology to Earthly Labs, which was building a portfolio of carbon-capture technologies. Earthly Labs launched its CiCi carbon-capture system, designed for small breweries, in 2018. Priced at around $75,000, the most popular model captures between 45,000 and 113,000 kg of CO2 per year, Earthly Labs CEO Amy George tells Newscripts.

Denver Beer’s Berger says that could give a good return on investment for operations putting out anything more than a couple thousand barrels per year—his brewery makes around 21,000. The move is also good for the environment and good marketing. “Consumers are definitely going to buy a greener beer,” Berger says. It’s made Denver Beer more green in other ways too. The Earthly Labs system recovers more CO2 than the brewery needs, so Berger sells his surplus CO2 to a local indoor marijuana farm.

A new whey to make liquor

Credit: C&EN/Shutterstock

Cow cocktails: Distillers are turning excess whey into gin and vodka.

IBreweries aren’t the only ones finding better boozy uses for their by-products. Distilleries in the UK, US, and Australia have started making gin and vodka from whey. Whey is the watery fraction of milk left over from cheese making. Whey is made into ricotta, processed into protein powder, fed to pigs, or just dumped.

Lactose is a disaccharide that normal brewer’s yeast, Saccharomyces cerevisiae, can’t ferment. In fact, brewers add lactose to some types of beer, such as milk stouts, when they want sweetness in the final product. But other yeasts, especially Kluyveromyces marxianus, can split lactose into glucose and galactose and ferment those into ethanol, explains Matt Hartings, a chemistry professor at American University.

The methods for making alcohol from whey were developed in Ireland’s dairy country, says Antony Jackson, one of the distillers behind Bertha’s Revenge gin. “There is a complexity in the mouthfeel that we don’t get from grain-based spirits,” he tells Newscripts from his home in Ireland. “You can compare it to drinking a wine. It coats the mouth and releases the botanicals gently.”

Hartings explains that the difference in flavor and mouthfeel has more to do with the yeast than the whey feedstock. “Being chemists, we think of vodka as 60% water and 40% ethanol.” But different yeasts produce different secondary metabolites, and those can change the spirit’s character even at trace concentrations, he says. “It starts with the sugar, but the yeast is the difference maker.”

Craig Bettenhausen wrote this week’s column. Please send comments and suggestions to newscripts@acs.org.